It doesn’t require constant "phoning home" to a cloud server.
Originally known as a fast image viewer, ACDSee evolved into the "Pro" series to compete with emerging giants like Adobe Lightroom. Version 6.0 focused heavily on speed and native 64-bit support. This allowed the software to utilize more system RAM, which was crucial for processing the increasingly large RAW files produced by DSLR cameras of that period. Technical Milestones in Build 169 ACDSee Pro v6.0 build 169 -64bit- With Key -iahq76-
ACDSee Pro v6.0 Build 169 (64-bit): A Legacy Milestone in Digital Asset Management It doesn’t require constant "phoning home" to a